Stay bolt



Sept. l, 1925.

J. F. L. BAKER swr Bom X Filed Jan. l1. 19,24

LfO/Wg FLLjBae 311.11m l fot @ttor 1 w 14 a citizen of the UnitedStates, residing at pertains more particularly'. to boiler stayrPatented Sept. y Y

Y s l ES 1,551,731 PATENT OFFICE;` i

JOHN HL. BAKER, OF SAGINAW,` MICHIGAN, AssIGNoa To THE wrcxns BOILERco.,

i OFSAGINAW, MICHIGAN, A CORPORATION or MICHIGAN.

STAY BOLT.

Appiicatiqn mea January 11,1924. serial No. 685,585.

To all .whom #may concern.' Y. i

y Be it known that I, JOHN F.- L. BAKER,

Saginaw, iny the county lof Saginaw and State ofv Michigan,- haveinvented certain new and 'useful Improvements inf'Stay Bolts; and ,Iy dohereby declare the following to be a-full, clear,land exact descriptionof theinvention, such as will enable others skilled inthe artftoL whichit appertains to make and' use thesa'me.'V

This' invention relatesuto stay vbolts and boltsfused for'reinforcingifiat surfaces ysuch as `the `platestl'iat form ythe wallsofthe steam and Waterflegs;otlwater tube boilers.

In a previous Patent, No. 1,411,261", issued "April4, '1922, Idescribedand claimed avstay bolt so constructed that it can'quickly andeasily be applied to the plates of a boiler.

. In my previous yconstruction the bolt body was enlarged ynear bothends, one enlargef ment being underneath vthe head and tapered,

Athe other;` arrangementnearl the threaded end ofthe boltvand;cylindrical.V yIn the patent referred togthe ytightness of titbetweenthis cylindrical enlargement and its hole in .the plate`was.attainedjby means of '5U Vinto placeby the nut.A j) v a taperedcompressible `metal `ring, vkforced In that construction he,4cylindrical .enlargement on the bolt required ahole in the y plate oflarger diameter thanthefbody fof tained by the present' constructionissecurr `the bolt. My present construction employs a hole of smallerydiameterthanthe body of the bolt' c if ifi I E Thefimporta t kpractical.adyantzige hat,-y

'ng a.maximumof rannular plateiarea gripped `by the flat face. of thebolt, Iaswell as tight fits in the plates. i Maximum clamping land platereinforcing action is thus; secured to prevent bulging ofthe unsupportedplate area between the stay bolts of aboiler. v s

'W ith the foregoingand certain other objects inV View lwhich willappear `later in the specifications my invention comprises the devicesdescribed and claimed equivalents thereof.

My invention'is illustrated, in the vaccomand the panying drawing,'bein'gja partifsectional View, ythe bolt being shown fas applied ,to

" the legof a water'tube boiler,

As is `clearly shown in the drawing, the

device consists in a stay bolt adapted to fasten together in spacedrelation thetwo plates 1 yand 2 which comprise the side walls kot thewaterleg. of a boiler, for example the outer plate and tube sheet. `Theouter plate l is formed with a tapered hole 3, and

.tube sheet 2 has asimilar but somewhat The space*betweenplates 1 andl 2represent any space under pressure, as for example, the water space orsteam yspace ot the boiler.

The y'stay bolt is insertedby first placing Y thethimblef 13 toregisterl with the openings 3 and 4, then Ypassing the vstay boltthroughv the'opening 4 of plate 2 until the-tapered end 9 is receivedinto the tapered opening of platel;A At the same time the taperedpart7fat,.tlie head end of the bolt enters the'tapered opening 4-ofplate 2..

The relation between the length ofthimble 13 and the spacing of thetapers 7 and 9 Aissuch that both of these two tapers seat simultaneouslyand litr theirl respective Vtapered holes: correctlyA when theI boltk isdriventiglitunderthe pull of nut 12, Y

The bottom 0fL he nut is preferablyfaced to Vpresentan area forv uniformbearing against .the outer tacel of plate 1. Y

The platel on one side is supported bythe Y end of the thimbleland onthe other side` by tlieflatl'faceof nut 12. YInternal pressureobviouslytends to bulge plate 1 at any unsupported area, as indicated inan exaggerated manner by the dotted'lines'at 14.

But this bulging tendency is in my present construction reduced to aminimum because of the fact that the area X of the plate around theopening 3 is uniformly supported by nut 12. lhen clamped in this mannerVand subjected to internal pressure the plate acts like a beamsupportedand liXed at both ends. Consequently: the ability of theunsupported area to resist the bulging tendency `01E internal pressure,is Inreziss .and the tendency'to deflect'is correspondingly lessened.

The tube sheet 2 shown at the left in the drawing is partly supported bythe'tubes 15 in those areas that are notstalyed by bolts" 5. Therefore,it is not necessary in practice to provide the tube sheet 2 with anextensive clamping area around the openinget. Bolt head 6 may be madewith a relatively small diameter since the direction of taper 7 isopposite the internal pressure.

The construction and arrangement of the stay bolt herein described welladapts it for economical quantity production from bar stock, the onlyoperations required being those which can be readily performed in aturning' lathe or thread miller.' y

The tapered' faces of the openings 3 and 4L are ream'ed and the tapers 7and 9 on the boltY are machined to .lit the faces closely andaccurately. rlhe thimble or spacer 13 is also made accurately to length.The distance between the faces of plates 1 and 2 as-ixe'd by thimble 13is suchthat the tapers '7 and 9 simultaneously seat in the taperedopenings t and 3 when .nut 12 is forced to its'final seat upon the outerface 'of plate 1.

By the combination of the thim'ble 13, thetaper 9 andthe Hat faced nut12 I have developed a new inode of operation in stay bolt practice.Heretofore several stay bolt designs have been accepted and approvedwithin certain technical limits by the various underwriters2 codes forboiler design, as forexample, a stay bolt threaded throughout vitslength and screwed into both plates, the outer ends of said boltriveted. ln another accepted construction the riveting' lof thest'aybolt end is omitted and vinstead nuts are threaded on the bolt'ends. A still further accepted arrangement employs av metal washerbetween the plate-rand nut. The stay bolts that impart the 'greatest'reinforcing effect to the. plate surroundingthebolt opening're'ceive'.the most favorable ratings, as will be apparent from. the'follc'nving`eX- ample: f i The U. Symarine formula foi'coin'puting allowable workingpressure is,' divide th'e square ofthe platethie'knessexpressed ininches by the squareoftlie pitch of the stay bolts lin 'sixteenthsof aninchandmultiply the quotient by a constant, the 'value ofwhich has beendetermined by experiment and differs with different types of stay bolts.A threadedsta'y bolt with riveted'ends is allowed a constant equal to''112. there a nut is used instead of the riveted end the allowedconstant is 120 and where a thimble is eirployed with a bolt having ataper under the head'of the bolt, as in my patent above referred to, the`allowed constant is higher. lt is thus seen that the value of theconstant, and consequently the allowable working` pressure for a giventhickness of plate increases as the effectiveness of clamping the platearea that surrounds the bolt hole, is increased.

This clamping effect is greatly increased in my present constructionbecause the slight endwise play of the plates 1 and 2, with respect tothe two tapers 7 and 9 on the bolt, when nut 12 is Vtightenedallows thethiinble 18 to act as a hollow lcoluinn clamped endwise between platesland 2. Moreover, the bolt with its taper 9, the thimble 13 and nut whenassembled together as herein described, provide the full equivalent of aheavy reinforcing ring on the plate around the bolt opening. v Havingthus describedniy invention, what l claim and desire to secu'rebyLetters Palent is:

ln combination, a pair of plates spaced apart, a thiinble between saidplates, each plate formed with a Atapered aperture ex.- tendingtherethrough, the aperture of one plate of larger diameter' than theaperture o l` the other' plate, and the tapers inthe opposing.;` platesbeing' in the same direction, n bolt comprisingv a body, a head, athreaded end, and a nuttherefor, a-part of said bolt body adjacent thehead tapered to lit the aperture of one 'of sai'dvplates, a part of saidbolt body'adja'cent the threaded end tapered Vto iitithefaperture loftheother plate", w 1ere! by` ti ,rhteningv saidv nutV produces Ven'dwisecompression in' Asaid thnnbleI and draws both of the tapered parts ofsaid bolts simulta `neously into'close' engagement with the walls fofthe tapered openings '1n the respective plates.

` lui-testimony whereof,-I affix my signature.

.TOI-IN F; L. BAKER. Y

